On May 7, 1999, about 1825 Alaska daylight time, a wheel equipped Aeronca 15AC airplane, N1315H, sustained substantial damage during an emergency landing and ditching, about 35 miles east of Pedro Bay, Alaska. The airplane was being operated as a visual flight rules (VFR) personal flight under Title 14, CFR Part 91, when the accident occurred. The solo commercial pilot sustained serious injuries. Visual meteorological conditions prevailed, and a VFR flight plan was filed. The flight originated at the Pedro Bay Airport, about 1800, and was en route to Soldotna, Alaska. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on May 8, the pilot reported that while climbing through 7,000 feet msl, approaching the coast of Chinitna Bay, he smelled smoke in the airplane, followed by a rough running engine. He made a 180 degree turn to return to Pedro Bay, and then saw smoke and flames coming from underneath the floor boards adjacent to the rudder pedals. He then advised the Kenai Flight Service Station (FSS) that he was making an emergency descent, and that he would be attempting to land on a tidal beach within Chinitna Bay. During the emergency descent, the airplane cabin filled with smoke, hindering his vision. The pilot said that the top portion of the clamshell door was torn off when he attempted to clear the smoke from the cockpit area by opening the door during the emergency decent. The pilot said, in part: "My legs were on fire and I just wanted to put the fire out, and get the airplane on the ground." The pilot landed in the water, just short of the beach, and the airplane nosed over upon touchdown. After ditching, the fire was self-extinguished by ocean water, and the pilot waded ashore. The airplane sustained substantial damage to the wings, and fuselage. A Federal Aviation Administration (FAA) airworthiness inspector from the Anchorage Flight Standards District Office, traveled to the accident scene on June 23, 1999, and examined the airplane wreckage. The inspector reported that the engine compartment, firewall, instrument panel, and floor boards exhibited heavy fire damage. He said that upon closer inspection of the engine, it was discovered that the top portion of the number three cylinder was separated between the cylinder barrel and the cylinder head. He added that the main fuel supply line was burned through, and disconnected from the carburetor attach point. In a written statement the FAA inspector wrote, in part: "...the vibration shook loose the left engine exhaust pipe which then directed the exhaust onto the fuel line to the carburetor which caused the fire."